PURPOSE:To improve the longitudinal propagation speed without reducing the internal loss, by using a polyethylene fiber in which the longitudinal propagation speed is a specific value or over as an acoustic member for a speaker diaphragm. CONSTITUTION:Polyethylene fibers on market and polyethylene fibers having =4,000m/sec in longitudinal propagation speed are cut into a prescribed size and diffused in water, paper-made into sheet shape by exfoliating deposited fiber layers on a wire cloth. Further, the sheet is formed into a film with a vacuum press to form the diaphragm. The longitudinal propagation speed of the diaphragm is increased much more than that of the polyethylene fibers on market, allowing to prevent the reduction in the internal loss of the diaphragm.
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